Telephone-exchange system.



J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION men SEPT.24. 19:4. RENEWED APR. 20. 1918.

Patented N 0v. 12, 1918.

2 SHEETS-SHEET I.

PVlT/VESSES AM, WW/M 0 V @zv/ J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 24. 1914. RENEWED APR-20.1918.

Patented Nov. 12, 1918.

2 SHEETS-SHEET 2.

U WITNESSES i mm jm I [MM AZZM/ UNITED s'ra'rns Parnn onnion.

JOSEPH L. WRIGHT, OF CLEVELAND, OHIO, ASSIGNOR, BY'MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Tatent.

Patented Nov. 12, 1918.

Application filed September 24, 1914, Serial No. 863,374. Renewed April 20, 1918. Serial No. 229,870.

"State of Ohio, have invented certain new anduseful Improvements in Telephone-EX- change Systems, of which the following is a specification.

My invention relates to telephone exchange systems and particularly to that type employing automatic switches for interconnecting subscribers lines. The main object of my invention is to provide improved means for efiecting connection between calling lines and trunks.

One of the features of the invention is the provision of a novel circuit arrangement for systems wherein calling lines are extended to connectin circuits b r automatic finder switches.

Another feature relates to the means for allowing the calling party to release the automatic finder switch while maintaining the connecting circuit to which it belongs inaccessible to other calling subscribers until the operator disconnects the called end of the connecting circuit from the called line.

My invention is illustrated in the accompanying drawings, wherein Figure 1 shows subscribers line circuits and the central office controlling mechanism.

2 shows a trunk switch terminating on a plug.

Referring to Fig. 1, I have shown the central otlice equipments associated with the lines of two subscribers but I have only shown substation equipment of one line at A.

This substation equipment consists of apparatus usual 'in common battery equipments.

The line from substation A terminates at the central office on a line relay B through the contacts of the cutoff relay C. When energized the line relay sets in operation the control mechanism for starting and stopping a trunk switch such as O in Fig. The switch W is common to a group of lines and selects an idle trunk switch. The number of lines in the group can be arranged to suit ircumstances, while the number of trunk switches selecting a group of lines will be regulated according to traffic conditions.

Referring to Fig. 2, the trunk switch 0 is provided with the tip and sleeve wipers and 62 for engaging conductors extending to contacts of the cutoff relays of the lines. This switch 0 is also provided with a wiper 61 for operating these cutofi relays associated with the lines.

When connection is effected between the trunk and a calling line the operator receives a signal to that effect and thereupon obtains the number wanted and then places the trunk plug P into the j ack of the called line and rings in the usual manner.

The operation of the various parts can be best brought out in tracing a call from a calling to a called subscribers line.

We will assume that a call is originated atsubstation A by the removal of the receiver, thereby closing the line conductors. The closing of these conductors operates the line relay B through the contacts of the cutoff of relay C. WVhen relay B operates it is maintained locked to ground by the following path: battery X, winding of relay B, locking contacts, 4, back contacts of relay G to ground. The operation of relay B completes the circuit of the stepping magnet F of the switch W by the following path: ground, contacts of relay B, 7, contacts of relay Gr, 8, contacts of relay E, 23, winding of magnet F, contacts of relay D to battery XQ The operation of magnet F- causes its associated contact springs to be closed, thereby operating relay D. The op"' eration of this relay opens the circuit of the magnet F and the magnetF in restoring opens the circuit of the relay D. This action causes a vibration to be set up between the magnet F and the relay D. The operation of the magnet causes the switch W to rotate until the idle trunk such as shown in Fig. 2 is selected. When such a trunk is selected the test relay E associated with switch V is placed in series with relay H (Fig. 2) by the following path ground, contacts of relay B, 7, contacts of relay G, 8, winding of relay E, 9, switch W, 10, winding of relay H, 11, contacts of relay I, 12, contacts of relay L to batterv X.

The operation of relay E opens the circuit of magnet F, thereby causing the switch W to come to rest with its wiper engaging a contact 'leading to the idle trunk. This relay E will remain energized and the switch N at rest until the contacts of the calling line are engaged by the wipers of the switch 0.

The operation of relay H completes the circuit of the stepping magnet Y by the following path: ground, contacts of relay H, 50, contacts of relay 1, 51, contacts of relay Z, 52, the winding magnet Y to bat tery X. The operation of magnet Y closes its associated contact springs and operates relay Z and this relay in operating opens the circuit of magnet Y. Magnet Y restoring opens the circuit of relay Z and this relay in restoring again closes circuit of magnet This action causes a vibrating effect between the magnet Y and relay Z and the operation of the former causes the switch 0 carrying the wipers 60, 61 and 62 to rotate and pass over contacts leading respectively to the tip and sleeve conductors associated with lines and to the windings of the cutoff relays such as C.

The wiper 61 in passing over contacts leading to the windings of the various cutoff relays causes such relays if not already operated to become energized. Under normal conditions this causes no effect, but when the wiper 61 encounters a contact connected to the cutoff relay of the calling line which has its line relay B energized the following action takes place: As soon as relay C is energized by the wiper 61 engaging its associated contact the circuit of the control relay G is completed by the following pat-h: ground, contacts of relay B, 26, contacts of relay C, 25, 9A, winding of relay G to battery X. The operation of relay G opens the circuits of relays E and H by disconnecting ground which was connected to the winding of relay E through the contacts of relay B. Relay H restoring opens the circuit of the stepping magnet Y, thus causing the switch 0 to come to rest with its wipers engaging contacts associated with the calling line. The operation of relay C also removes ground from the locking contact of relay lVhile the switch 0 is rotating and relay H energized, battery X is connected directly to the wiper 61 through the front contact of relay H but after this relay is deenergized by the operation of relay G then this direct battery connection is removed and relay I placed in series with relay C. The operation of relay C disconnects the line relay B and connects the line conductors to the conductors extending to the contacts engaged by wipers 60 and 62. As soon as relay H restores battery and ground are connected respectively to the windings of relay J and the retardation coil K. Relay J and coil K are connected respectively to the tip and sleeve conductors of the trunk circuit and supply talking current to the calling subscriber. Relay J remains energized while the receiver is removed at the calling station.

Relay 1 in operating maintains the circuit 0f the stepping magnet Y disconnected and lights the signal lamp R by the following path: battery X, contacts of relay L, 12 contacts of relay 1, 32, lamp R, 33, con tacts of relay H to ground. The operation of relay I also opens the circuit of relay H to prevent its trunk circuit being selected by another call.

Relay G is a slow acting relay and is timed to hold its contacts open while the circuits are being shifted by the action of the relays previously described. After this relay fully restores it again places the switch TV in condition to select other trunks.

From the foregoing description it will be noted that no test device is associated with the trunk switches. These switches are simply started upon the origination of a call and the wipers in passing over the various contacts operate the cutoff relays of lines whether they are idle or whether they are in condition for originating calls. When the cutoff relay is operated and is associated with a line which is attempting to originate a call, then the control relay G is operated and opens the circuit which controls the starting and stopping of the trunk switch. The opening of this circuit which is common to plurality of trunk switches brings the active switch to rest, engaging contacts of a calling line.

The lighting of the lamp R in the manner previously described notifies the operator of a call and she, therefore, operates the listening key 102, thereby connecting her telephone set cross the trunk conductors, enabling her to converse with the calling subscriber. After learning the number desired she the jack of the called line in case multiple acks are used and determines whether such line is busy. In case the line is not busy the plug P is placed into the jack Q, causing relay L to be operated in series with the cut off relay of the called line. The operation of the cutoff relay disconnects the line relay and connects the line conductors to the conductors extending to the jack Q. The operation of relay L lights the supervisor lamp T and also disconnects wire. 12 from battery X to prevent the selection of the trunk so long the plug remains in the jack.

After the connection is effected with the called line the ringing key 100 is operated separating the trunk conductors and connecting current from generator U to the called line, The called subscriber answering in response to the call removes his re ceiver and energizes the tip relay M thereby extinguishing the lamp T.

After the calling subscriber replaces his receiver, the tip relay J becomes deengerized and the circuit of the release magnet V of the switch 0 is completed by the following path: batter X, contacts of relay L, 31 contacts of relay J, 30, winding of magnet with the trunk has its circuit completed in multiple with the magnet V and in lighting notifies the operator that the calling subscriber has replaced his-receiver.

Ihe called subscriber in replacing his receiver causes the de'c'nergization of relay M which in restoring allows the circuit of the lamp T to be completed and the lighting of-this lamp notifies the operator that the called subscriber has replaced his receiver. Upon receiving the two disconnect signals the operator withdraws the plug P from the jack Q, thereby causingthe restoration of relay L, which in restoring again connects battery to the winding of relay H, thus rendering this trunk circuit available for other calls.

'Referring to Fig. 1, it will be seen that proper selection will take place regardless of the fact whether there is but a single call originated at the same instant or whether there are a plurality of calls awaiting connection with trunk circuits. Whenever the selected trunk switch engages contacts associated with a line over which a call is origr nated the relay G is operated and the operation of this relay causes the trunk switch to remain in engagement with contacts of the calling line. As soon as this connection is efiected and when relay G fully restores the next selected trunk switch will operate and perform the same functions as previously described.

IVhile I have shown the trunk switch 0 terminating in the plug P, it will readily be understood that this is for purpose of illustration only. Instead of terminating on a plug the trunk switch mayterminate on a first selector switch which can be operated to select other selector or connector switches. The I operator in this instance would, of course, be provided with a sending device for operating selector and connector switches. Such arrangement is shown in Patent No. 818,5 l0 of April 2 1906, to Land.

It may be stated that the line relays as B of Fig. 1 can be rendered sluggish in their I action in restoring so as to increasethe duration of the impulse transmitted to relay G by the operation of a relay as'C. While the trunk switch is traveling and operates relay C it follows that the relayB is disconnected by the operation of its associated relay. C. Belay'B restoring, of course, opens the circuit to relay G, but if relay, B is rendered sluggish in its action an impulse of longer duration will naturally be transmitted to relay G.

Having thus described my invention what I desire to secure by Letters Patent is:

1. In a telephone exchange system, the combination with telephone lines, of a finder switch having fixed terminals for each line and a traveling contact adapted to wipe over said terminals successively, a driving circuit for said finder, line relays for said lines adapted to close said driving circuit, cut-01f relays for said lines connected to said terminals, circuits for successively operating said cut-oil relays completed as the traveling contact wipes over said terminals, and a relay operated by the actuation of the cut-off relay of the calling line adapted to open said'driving circuit.

2. In a telephone exchange system, the combination with telephone lines, of a finder switch having fixed terminals for each line and a traveling contact adapted to wipe over said terminals successively, a driving circuit for said finder, a stop relay controlling said driving circuit at a back contact, a line relay adapted to close said driving circuit and to prepare a circuit to energize said stop relay, cutoff relays for said lines connected to said terminals, circuits for successively operating said cut-ofi relays completed as the traveling contact wipes over said terminals, the cutoff relay of the calling line in operating closing said prepared circuit to operate said stop relay to open said driving circuit.

3. In a telephone exchange, the combination with telephone lines, a finderv switch having a fixed terminal for each line and a traveling contact adapted to engage said terminals successively, means actuated by the initiation of a call in any of said lines for operating said finder switch, relays individual to the lines, circuits for successively operating said relays completed by the finder switch as its traveling contact reaches the terminals of said lines, means permanently associated with said lines and actuated by the relay of the calling line to stop the switch upon the calling line terminal, a master switch, and means controlled by calling lines for causing said master switch to select an idle finder switch.

4C. In a telephone exchange system, the combination with telephone lines, a finder switch having a fixed terminal for each line and a traveling contact adapted to engage said terminals successively, a line relay and a cut-off relay for each line, means actuated by any line relay when operated to. cause said traveling contact to move over said fixed terminals, circuits for successively operating the cut-off relays of the lines as said contact wipes over said terminals, means permanently associated with said lines actuated by the operation of'the cut-off relay of the calling line for stopping said traveling contact, a master switch, and means controlled by said line relays for causing said master switch to select an idle finder switch.

5. In a telephone system, the combination with telephone lines, a relay individual to each of said telephone lines, a finder switch wherein said lines terminate, means controlled by any of said lines for causing said finder :itch to more, a relay common to and permanently associated with said lines for causing said finder switch to stop, a circuit for actuating said relay closed in a contact of the relay individual to the line calling when the finder reaches such line, a ma, ter switch, and means controlled by calling lines for causing said master switch to select an idle finder switch.

6. In a telephone exchange system, the combination with telephone lines, a finder having a fixed terminal for each line and a trayeling contact adapted to engage said terminals successively, a line relay and acut-oif relay for each line, a master switch for said finders, means actuated by any line relay when operated to cause said master switch to select an idle finder, means thereupon actuated for causing the traveling contact of. said finder to move over said fixed terminals. circuits for successively operating the cut-off relays of the lines as said contact wipes over said terminals, and means permanently associated with said lines actuated by the operation of the cut-off relay of the calling line for stopping said traveling contact upon such line.

7. In a telephone exchange system, the combination with telephone lines, line re lays therefor, connecting circuits, automatic finder switches for extending calling lines to said connecting circuits, electromagnetic driving means therefor, a master switch, electromagnetic driving means therefor, a circuit for said master switch electromagnetic driving means, the operation of any line relay closing said circuit, a test circuit including a brush of said master switch and said finders and prepared upon the operation of any line relay, a relay associated with each finder circuit, the relay of the selected idle finder becoming energized when the test circuit becomes closed as the master switch selects such finder, the operation of said relay energizing the electromagnetic driving means of such finder, a relay oper ated when said test circuit is closed to open the master switch driving circuit, and a relay operated when the finder selects the calling line to open said test circuit to render the seized finder busy and to deenergize said relay associated with the finder circuit to stop the finder.

8. In a telephone exchange system, the combination with telephone lines, line relays therefor, connecting circuits, automatic finder switches for extending calling lines to said connecting circuits, electromagnetic drivinn means therefor, a master switch, electromagnetic driving means therefor, a circuit for said master switch electromagnetic driving means, the operation of any line relay closing said circuit, a test circuit including a brush or said master switch and said finders and preparedupon the operation of any line relay, a relay associated with each finder circuit, the relay of the selected idle finder becoming energized when the test circuit becomes closed as the master switch selects such finder, the operation or" said relay energizing the electromagnetic driving means of such finder, and arelay operated when the finder selects the calling line to open said test circuit to render the seized finder busy and to deenergize said relay to stop the finder.

9. In a telephone exchange system, the combination with telephone lines, line relays therefor, connecting circuits, automatic finder switches for extending calling lines to said connecting circuits, electromagnetic driving means therefor, a master switch, electromagnetic driving means therefor, a circuit for said master switch electromagnetic driving means, the operation of any line relay closing said circuit, a test circuit including a brush of said master switch and said finders and prepared upon the operation of any line relay, a relay H associated with each finder circuit, the relay of the selected idle finder becoming energized when the test circuit becomes closed as the master switch selects such finder the operation of said relay energizing the electromagnetic driving means of such finder, a relay 1 operated when the finder selects the calling line to open said test circuit to render the seized finder busy and also to denergize said relay H to stop the finder, and a relay L operated when the connecting circuit is extended to the called line to open said test circuit at another point.

10. In a telephone exchange system, the combination with telephone lines, a connecting circuit including a normally resting automatic finder switch, means controlled by calling lines for causing said finder switch to extend a calling line to said connecting circuit, said connecting circuit terminating in manually controlled means for extending said connecting circuit to a called line means actuated by the extension of a calling line to a connecting circuit for rendering said connecting circuit inaccessible to other calling lines, means controlled by the call ing party for releasing the automatic switch only to its normal position, and means for maintaining the connecting circuit inaccessible to calling lines until restored by the operator.

11. In a telephone system, a finder switch having movable and stationary contacts,

telephone lines terminating in said station ary contacts, a link circuit terminating in said movable contacts, means controlled by any of said lines for causing the operation of said movable contacts, a relay common to and permanently associated with said lines for causin said movable contacts to stop, a circuit or said relay, means independent of the contacts of said finder switch 10 for closing said circuit when the finder switch reaches the calling line, a master switch, and means controlled by calling lines for causing said master switch to select an idle finder switch.

In testimony whereof I aflixmy signa- 15 Copies 01! this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). 0. 

